CX GTI Turbo. Thinking caps on!

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Bilkob
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Re: CX GTI Turbo. Thinking caps on!

Post by Bilkob » 20 Nov 2017, 21:04

Hmm, don't THINK so as it does bloody go when the bonnet is shut for driving!
But I'll check
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Re: CX GTI Turbo. Thinking caps on!

Post by wurlycorner » 20 Nov 2017, 21:27

Sounds light fuel starvation/evaporation when it gets hot.
I would check all the fuel lines for any visible cracks/splits/loose joints as a starting point and then maybe something like squirting easi-start over the system bit by bit (again, when it's hot).
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Re: CX GTI Turbo. Thinking caps on!

Post by Bilkob » 21 Nov 2017, 09:14

Does anyone know the part number for the fuel pressure regulator? CX GTI T1 (series 2)
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Re: CX GTI Turbo. Thinking caps on!

Post by xantia_v6 » 21 Nov 2017, 09:21

What drives the ignition coils on this setup?

You could try wrapping various components with a wet rag to see if the symptoms are delayed.
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Re: CX GTI Turbo. Thinking caps on!

Post by wurlycorner » 21 Nov 2017, 10:48

xantia_v6 wrote:
21 Nov 2017, 09:21
What drives the ignition coils on this setup?


Thanks to the wonders of Citroen at this time, on this model, it could be any one of three setups :lol:
Single pickup or dual pickup flywheel and tdc sensors, via the AEI unit.
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Re: CX GTI Turbo. Thinking caps on!

Post by Bilkob » 21 Nov 2017, 20:21

Mine has got twin flywheel sensors. They are now replaced with Ford items
I'm determined to sort this out, as it's such a great car, and ay help others too
So, overheating coils?
Knock sensor?
Air flow meter?
Cylinder head temp sensor?
Fuel pressure regulator?
Fuel pump?
A curse?!
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Re: CX GTI Turbo. Thinking caps on!

Post by wurlycorner » 21 Nov 2017, 22:45

Have you looked at my suggestion yet? You've jumped straight back to all the electrical items there...

And the knock sensor will only retard the ignition by a small amount and only if it hears knock (it is nothing more than a microphone on these really). It will not cause the engine to stall and cut out. Just unplug it if you have any concerns it is - from memory that should have no effect.
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Re: CX GTI Turbo. Thinking caps on!

Post by Bilkob » 22 Nov 2017, 18:27

Ok. More evidence.I've sprayed all the fuel, air, etc lines and pipes and joints in the engine bay with easy start/WD and not a jot of difference
I did find d a split in the rubber T that comes off the boost pipe, utility fixing this made no difference
I've also learned that it WILL cut out with the bonnet open too, same symptoms as closed
However, tonight I sat in it and waited for it to happen.
Just before it cuts, it stutters and if you catch it on the throttle it will splutter and keep going. When the spluttering gets really bad, the tacho needle starts jumping around and the throttle pedal becomes unresponsive
After it dies, it restarts 9 times out of 10, but sometimes with the tacho jumping and unresponsive throttle, sometimes not
I've read that these are classic symptoms of AEI issues but I've tried another one and that did the same!
Over to you lot!
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Re: CX GTI Turbo. Thinking caps on!

Post by Zelandeth » 22 Nov 2017, 18:35

The tacho jumping around immediately shouts to me of cranshaft position sensing issues.

Worth getting a scope involved and seeing if you've got a clean signal arriving at the ECU?

These don't have the weird warmup regulator setup like the K-Jetronic cars do they (which vary the mixture as the engine warms up by varying the fuel pressure)? If so, they can cause some downright strange behaviour when playing up. Talk of airflow meters though suggests its a more advanced setup...
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Re: CX GTI Turbo. Thinking caps on!

Post by Bilkob » 24 Nov 2017, 21:14

Ok, so, a few more clues.
The car seems to get 'less pleasant' to drive the longer it is running. It's as if, as it warms up, not to operating temperature but after extended running, everything just gets a bit bit 'less smooth'
Also, if you've pinned it's ears back (!) and then come to a stop, idling , the oil light flickers on, but blipping the throttle see it go out
Also, the more/harder it's run, there's a faint burnt oil smell, but there's no leaks onto or near the turbo
Today, I changed the coils back to the original single pack that was originally on the car and it made NO difference
The car has no overheating issues, fans cut in at about 90 c and the temperature falls back to 80 quite quickly
I've changed oil and filter ( that was fun)
I'm now wondering if I should try and fit an inline fuel pressure gauge?
Has anyone done this?
Also, with the cutting out, it'll now restart pretty much straight away (lower ambient?) But still with flicking tacho
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Re: CX GTI Turbo. Thinking caps on!

Post by white exec » 24 Nov 2017, 22:00

Oil light flickering on might just be idle speed too low (or result of running badly when hot), especially after a 'hot' run, when the oil will be thinner. Reassuring that it goes out as soon as engine speeds up.

Tacho flickering does suggest crankshaft (flywheel) sensor. Citroen speed sensors (flywheel, distance...) fairly well known for misbehaving.
Possible that the sensor that triggers tacho is also feeding other things, including engine ECU.

Check sensor tip for wear/damage and steel dust/debris - tips are magnetic. The closer the sensor tip to the metal peg/whatever that it's triggered by, the better. 1-2mm usually does it. Check sensor connector for cleanliness and contact too; signal produced is minuscule.
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Re: CX GTI Turbo. Thinking caps on!

Post by Bilkob » 25 Nov 2017, 07:50

The sensors are new Ford items, the connectors were spotlessly clean. Where is the sensor that triggers the tacho?
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Re: CX GTI Turbo. Thinking caps on!

Post by wurlycorner » 26 Nov 2017, 11:04

Ah, Now you tacho bouncing, I agree this now sounds more like flywheel pick up and/or other aei system related fault and it must be something breaking down in the heat.

Could potentially be low voltage causing the electronics to fail? Try fitting a voltage meter somewhere so you can see if the alternator output voltage is dropping off when the car gets hot and at idle.

How like-like were the replacement Ford flywheel sensors and why were they replaced in the first place? We're the old ones definitely u/s? I would suggest swapping back to the oem items. Also did you check that the gap between the new sensors and the flywheel teeth and the TDC marker were the same for the new as on the original?
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2x '85 CX GTi Turbo s1 (metallic blue and green)
2x '85 CX GTi Turbo s2 t1 (metallic silver and grey)
'88 CX GTi Turbo s2 T2 (metallic light blue)
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Re: CX GTI Turbo. Thinking caps on!

Post by wurlycorner » 26 Nov 2017, 11:09

If you want to pop over one day next weekend I don't mind spending a few hours poking about on it with you if you like?
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2x '85 CX GTi Turbo s1 (metallic blue and green)
2x '85 CX GTi Turbo s2 t1 (metallic silver and grey)
'88 CX GTi Turbo s2 T2 (metallic light blue)
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'01 C5 2.0 HDi LX Estate (Blue)

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Re: CX GTI Turbo. Thinking caps on!

Post by wurlycorner » 23 Dec 2017, 11:23

Just wondering how things are getting on?
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2x '85 CX GTi Turbo s1 (metallic blue and green)
2x '85 CX GTi Turbo s2 t1 (metallic silver and grey)
'88 CX GTi Turbo s2 T2 (metallic light blue)
CX DTR T2 Safari (silver)
2x '96 Xantia Activa (Black and Metallic Green)
'01 C5 2.0 HDi LX Estate (Blue)